Field of the Invention
Embodiments of the present disclosure relate generally to power conversion and, in particular, to regulating an input voltage to a power converter.
Description of the Related Art
Use of distributed generators (DGs) to produce energy from renewable resources is steadily gaining commercial acceptance due to the rapid depletion of existing fossil fuels and the increasing costs of current methods of generating power. One such type of DG may be a solar power system comprising a plurality of photovoltaic (PV) modules that convert solar energy received from the sun into a direct current (DC). One or more inverters then convert the DC current from the PV modules into an alternating current (AC). The AC power generated may then be used to run appliances at a home or business, or may be coupled to the commercial power grid and sold to the commercial power company.
One type of inverter that may be utilized for such DC-AC power conversion is a current source inverter (CSI). A CSI inverter is the dual of a voltage source inverter (VSI); for a CSI, the DC power supply is configured as a current source rather than a voltage source as for the VSI. One advantage of the CSI is that it increases the voltage towards the grid, negating the need for an additional DC-DC boost stage generally required by a VSI. Such an increase in voltage requires that the input voltage to the CSI must be lower than its output voltage.
In some large-scale DG installations, such as utility-scale installations, the grid voltage may drop, requiring additional power to be injected from the DG onto the grid to maintain operation of the grid. Such a drop in grid voltage may result in an output voltage at the CSI that is lower than the CSI input voltage, causing an unstable condition where current generation by the CSI cannot be controlled.
Therefore, there is a need in the art for a method and apparatus for regulating an input voltage to a power conversion module.